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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Publication Detail

Title: DMPS-arsenic challenge test. II. Modulation of arsenic species, including monomethylarsonous acid (MMA(III)), excreted in human urine.

Authors: Aposhian, H V; Zheng, B; Aposhian, M M; Le, X C; Cebrian, M E; Cullen, W; Zakharyan, R A; Ma, M; Dart, R C; Cheng, Z; Andrewes, P; Yip, L; O'Malley, G F; Maiorino, R M; Van Voorhies, W; Healy, S M; Titcomb, A

Published In Toxicol Appl Pharmacol, (2000 May 15)

Abstract: The administration of sodium 2,3-dimercapto-1-propane sulfonate (DMPS) to humans chronically exposed to inorganic arsenic in their drinking water resulted in the increased urinary excretion of arsenic, the appearance and identification of monomethylarsonous acid (MMA(III)) in their urine, and a large decrease in the concentration and percentage of urinary dimethylarsinic acid (DMA). This is the first time that MMA(III) has been detected in the urine. In vitro biochemical experiments were then designed and performed to understand the urinary appearance of MMA(III) and decrease of DMA. The DMPS-MMA(III) complex was not active as a substrate for the MMA(III) methyltransferase. The experimental results support the hypothesis that DMPS competes with endogenous ligands for MMA(III), forming a DMPS-MMA complex that is readily excreted in the urine and points out the need for studying the biochemical toxicology of MMA(III). It should be emphasized that MMA(III) was excreted in the urine only after DMPS administration. The results of these studies raise many questions about the potential central role of MMA(III) in the toxicity of inorganic arsenic and to the potential involvement of MMA(III) in the little-understood etiology of hyperkeratosis, hyperpigmentation, and cancer that can result from chronic inorganic arsenic exposure.

PubMed ID: 10814555 Exiting the NIEHS site

MeSH Terms: Adult; Animals; Arsenic Poisoning/prevention & control; Arsenicals/urine*; Cacodylic Acid/urine*; Chelating Agents/administration & dosage; Chelating Agents/metabolism; Chelating Agents/pharmacology; Chelating Agents/therapeutic use; Female; Humans; Liver/drug effects; Liver/enzymology; Male; Methyltransferases/antagonists & inhibitors; Middle Aged; Organometallic Compounds/urine*; Rabbits; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.; Unithiol/administration & dosage*; Unithiol/metabolism; Unithiol/pharmacology; Unithiol/therapeutic use; Water Pollutants

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